2,7-Dichlorofluorescein, a fluorescent sensor to detect Cd²⁺ over Na⁺, K⁺, Ca²⁺, Cu²⁺, Ni²⁺ and Zn²⁺

Abstract

The intensity of the fluorescent emission spectra of 2,7-dichlorofluorescein (510-640 nm) on excitation with 350 nm enhances on interaction with Cd²⁺ ions. Minor enhancement is observed with Na⁺ and Zn²⁺ ions, while no enhancement at all in fluorescence is observed with K⁺, Ca²⁺, Cu²⁺ and Ni²⁺. The enhancement in the fluorescence is explained on the basis of photoinduced electron transfer (PET) mechanism due to the binding of two Cd²⁺ ions to 2,7-dichlorofluorescein (log b = 3.80).